Zhimin Zhou
A5100406525- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Advanced SAR Imaging Techniques
- Microwave Imaging and Scattering Analysis
- Stellar, planetary, and galactic studies
- Synthetic Aperture Radar (SAR) Applications and Techniques
- Gamma-ray bursts and supernovae
- Geophysical Methods and Applications
- Radar Systems and Signal Processing
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Cosmology and Gravitation Theories
- CCD and CMOS Imaging Sensors
- Scientific Research and Discoveries
- Astronomical Observations and Instrumentation
- Soil Moisture and Remote Sensing
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Metallic Glasses and Amorphous Alloys
- Dark Matter and Cosmic Phenomena
- Magnetic properties of thin films
- Sparse and Compressive Sensing Techniques
- Infrared Target Detection Methodologies
- Remote-Sensing Image Classification
- Magnetic Properties and Applications
University of California, Berkeley
2023-2025
National University of Defense Technology
2015-2024
National Astronomical Observatories
2015-2024
Chinese Academy of Sciences
2015-2024
Eastern Institute of Technology, Ningbo
2024
Shanghai Jiao Tong University
2004-2024
Ural Federal University
2024
University of Chinese Academy of Sciences
2024
Dalian Institute of Chemical Physics
2010-2024
Zhejiang University
2024
Abstract Over the next 5 yr, Dark Energy Spectroscopic Instrument (DESI) will use 10 spectrographs with 5000 fibers on 4 m Mayall Telescope at Kitt Peak National Observatory to conduct first Stage IV dark energy galaxy survey. At z < 0.6, DESI Bright Galaxy Survey (BGS) produce most detailed map of universe during dark-energy-dominated epoch redshifts >10 million galaxies spanning 14,000 deg 2 . In this work, we present and validate final BGS target selection survey design. From Legacy...
Abstract The Dark Energy Spectroscopic Instrument (DESI) is carrying out a five-year survey that aims to measure the redshifts of tens millions galaxies and quasars, including 8 million luminous red (LRGs) in redshift range 0.4 < z ≲ 1.0. Here we present selection DESI LRG sample assess its spectroscopic performance using data from Survey Validation (SV) first two months Main Survey. sample, selected g , r W 1 photometry Legacy Imaging Surveys, highly robust against imaging systematics....
Abstract We describe the spectroscopic data processing pipeline of Dark Energy Spectroscopic Instrument (DESI), which is conducting a redshift survey about 40 million galaxies and quasars using purpose-built instrument on 4 m Mayall Telescope at Kitt Peak National Observatory. The main goal DESI to measure with unprecedented precision expansion history universe baryon acoustic oscillation technique growth rate structure space distortions. Ten spectrographs three cameras each disperse light...
Abstract The Dark Energy Spectroscopic Instrument (DESI) survey will measure large-scale structures using quasars as direct tracers of dark matter in the redshift range 0.9 < z 2.1 and Ly α forests quasar spectra at > 2.1. We present several methods to select candidate for DESI, input photometric imaging three optical bands ( g , r ) from DESI Legacy Imaging Surveys two infrared (W1, W2) Wide-field Infrared Survey Explorer. These were extensively tested during Validation DESI. In this...
Abstract A system of 5020 robotic fiber positioners was installed in 2019 on the Mayall Telescope, at Kitt Peak National Observatory. The robots automatically retarget their optical fibers every 10–20 minutes, each to a precision several microns, with reconfiguration time fewer than 2 minutes. Over next 5 yr, they will enable newly constructed Dark Energy Spectroscopic Instrument (DESI) measure spectra 35 million galaxies and quasars. DESI produce largest 3D map universe date expansion...
In 2021 May, the Dark Energy Spectroscopic Instrument (DESI) began a 5 yr survey of approximately 50 million total extragalactic and Galactic targets. The primary DESI dark-time targets are emission line galaxies (ELGs), luminous red (LRGs) quasars (QSOs). bright time, will focus on two surveys known as Bright Galaxy Survey (BGS) Milky Way (MWS). also observes selection "secondary" for bespoke science goals. This paper gives an overview publicly available pipeline (desitarget) used to...
Abstract The Dark Energy Spectroscopic Instrument (DESI) will precisely constrain cosmic expansion and the growth of structure by collecting ∼40 million extragalactic redshifts across ∼80% history one-third sky. Emission Line galaxy (ELG) sample, which comprise about all DESI tracers, be used to probe universe over 0.6 < z 1.6 range, including 1.1 is expected provide tightest constraints. We present target selection for Survey Validation (SV) Main ELG samples, relies on imaging Legacy...
We describe the Milky Way Survey (MWS) that will be undertaken with Dark Energy Spectroscopic Instrument (DESI) on Mayall 4m telescope at Kitt Peak National Observatory. Over next 5 yr DESI MWS observe approximately seven million stars Galactic latitudes |b|>20 degrees, an inclusive target selection scheme focused thick disk and stellar halo. also include several high-completeness samples of rare types, including white dwarfs, low-mass within 100pc Sun, horizontal branch stars. summarize...
Abstract A key component of the Dark Energy Spectroscopic Instrument (DESI) survey validation (SV) is a detailed visual inspection (VI) optical spectroscopic data to quantify metrics. In this paper we present results from VI quasar using deep coadded SV spectra. We show that majority (≈70%) main-survey targets are spectroscopically confirmed as quasars, with ≈16% galaxies, ≈6% stars, and ≈8% low-quality spectra lacking reliable features. nonnegligible fraction quasars misidentified by...
Abstract The Dark Energy Spectroscopic Instrument (DESI) Survey has obtained a set of spectroscopic measurements galaxies to validate the final survey design and target selections. To assist in these tasks, we visually inspect DESI spectra approximately 2500 bright galaxies, 3500 luminous red (LRGs), 10,000 emission-line (ELGs) obtain robust redshift identifications. We then utilize inspected information characterize performance operation. Based on visual inspection (VI) catalogs, our...
Abstract The Dark Energy Spectroscopic Instrument (DESI) is currently measuring the spectra of 40 million galaxies and quasars, largest such survey ever made to probe nature cosmological dark energy. 4 m Mayall telescope at Kitt Peak National Observatory has been adapted for DESI, including construction a 3.°2 diameter prime focus corrector that focuses astronomical light onto 0.8 focal surface with excellent image quality over DESI bandpass 360–980 nm. wide-field includes six lenses, as...
Abstract We present the final data from Sloan Digital Sky Survey (SDSS) Reverberation Mapping (RM) project, a precursor to SDSS-V Black Hole Mapper RM program. This set includes 11 yr photometric and 7 spectroscopic light curves for 849 broad-line quasars over redshift range of 0.1 < z 4.5 luminosity L bol = 10 44−47.5 erg s −1 , along with spectral variability measurements. report 23, 81, 125, 110 lags (relative optical continuum variability) broad H α β Mg ii C iv using SDSS-RM sample,...
ABSTRACT We present the first comprehensive halo occupation distribution (HOD) analysis of Dark Energy Spectroscopic Instrument (DESI) One-Percent Survey luminous red galaxy (LRG) and Quasi Stellar Object (QSO) samples. constrain HOD each sample test possible extensions by fitting redshift-space 2-point correlation functions in 0.15 &lt; r 32 h−1 Mpc a set fiducial redshift bins. use AbacusSummit cubic boxes at Planck 2018 cosmology as model templates forward clustering with AbacusHOD...
ABSTRACT This paper provides a comprehensive overview of how fitting baryon acoustic oscillations (BAO) is carried out within the upcoming Dark Energy Spectroscopic Instrument’s (DESI) 2024 results using its DR1 data set, and associated systematic error budget from theory modelling BAO. We derive new showing non-linearities in clustering galaxies can cause potential biases measurements isotropic ($\alpha _{\mathrm{iso}}$) anisotropic _{\mathrm{ap}}$) BAO distance scales, these be effectively...
Abstract Changing-look active galactic nuclei (CL AGNs) can be generally confirmed by the emergence (turn-on) or disappearance (turn-off) of broad emission lines (BELs), associated with a transient timescale (about 100 ∼ 5000 days) that is much shorter than predicted traditional accretion disk models. We carry out systematic CL AGN search crossmatching spectra coming from Dark Energy Spectroscopic Instrument and Sloan Digital Sky Survey. Following previous studies, we identify AGNs based on...
The Beijing–Arizona Sky Survey (BASS) is a wide-field two-band photometric survey of the northern Galactic Cap using 90Prime imager on 2.3 m Bok telescope at Kitt Peak. It four-year collaboration between National Astronomical Observatory China and Steward Observatory, University Arizona, serving as one three imaging surveys to provide input catalogs for target selection Dark Energy Spectroscopic Instrument (DESI) project. BASS will take up 240 dark/gray nights cover an area about 5400 deg2...
Stepped-frequency waveforms can achieve an ultrawide bandwidth by using a sequence of single-frequency pulses. The advantages stepped-frequency are low hardware requirements and high resolution. However, the waveform requires long time period to transmit signals, which limits its application in synthetic aperture radar (SAR). available imaging range width is usually very narrow, unless azimuth resolutions both decreased. In this paper, random-frequency SAR scheme based on compressed sensing...
Abstract Millions of quasar spectra will be collected by the Dark Energy Spectroscopic Instrument (DESI), leading to a fourfold increase in number known quasars. High-accuracy classification is essential tighten constraints on cosmological parameters measured at highest redshifts DESI observes ( z > 2.0). We present spectral templates for identification and redshift estimation quasars Year 1 data release. The are comprised two eigenspectra sets, trained from Sloan Digital Sky Survey. sets...
ABSTRACT We present the one-dimensional Ly α forest power spectrum measurement using first data provided by Dark Energy Spectroscopic Instrument (DESI). The sample comprises 26 330 quasar spectra, at redshift z &gt; 2.1, contained in DESI Early Data Release and 2 months of main survey. employ a Fast Fourier Transform (FFT) estimator compare resulting to an alternative likelihood-based method companion paper. investigate methodological instrumental contaminants associated with new...
Importance Endovascular therapy (EVT) demonstrated better outcomes compared with medical management in recent randomized clinical trials (RCTs) of patients large infarct. Objective To compare EVT vs across different strata the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) and infarct core volume Design, Setting, Participants This prespecified secondary analysis subgroups Therapy Acute Anterior Circulation Large Vessel Occlusive Patients With a Infarct Core (ANGEL-ASPECT)...
Abstract The One-Percent survey of the Dark Energy Spectroscopic Instrument collected ∼ 270 k emission line galaxies (ELGs) at 0.8 < z 1.6. high completeness sample allowed clustering to be measured down scales never probed before, 0.04 Mpc/ h in r p for projected 2-point correlation function (2PCF) and 0.17 galaxy pair separation s 2PCF monopole quadrupole. most striking feature measurements is a strong signal smallest scales, below 0.2 1 . We analyse these data halo occupation...
Abstract We detect the cross-correlation between 2.7 million DESI quasar targets across 14,700 deg 2 (180 quasars -2 ) and Planck 2018 CMB lensing at ∼30 σ . use on very large scales to constrain local primordial non-Gaussianity via scale dependence of bias. The lie an effective redshift 1.51 are separated into four imaging regions varying depth image quality. select from Legacy Survey DR9 imaging, apply additional flux photometric cuts improve purity reduce fraction unclassified redshifts,...
ABSTRACT We use angular clustering of luminous red galaxies from the Dark Energy Spectroscopic Instrument (DESI) imaging surveys to constrain local primordial non-Gaussianity parameter fNL. Our sample comprises over 12 million targets, covering 14 000 deg2 sky, with redshifts in range 0.2 &lt; z 1.35. identify Galactic extinction, survey depth, and astronomical seeing as primary sources systematic error, employ linear regression artificial neural networks alleviate non-cosmological...
Abstract The Dark Energy Spectroscopic Instrument (DESI) cosmology survey includes a Bright Galaxy Survey (BGS), which will yield spectra for over 10 million bright galaxies ( r < 20.2 AB mag). resulting sample be valuable both cosmological and astrophysical studies. However, the star/galaxy separation criterion implemented in nominal BGS target selection algorithm excludes quasar host addition to bona fide stars. While this excluded population is comparatively rare (∼3–4 per square...